Process of making brushes



y 22, 1952 i B. E- SUGERMAN ETAL I 2,604,362

' PROCESS OF MAKING BRUSHES Filed Dec. 1, 1947 Patented July 22, 1952PROCESS OF MAKING BRUSHES Bernard E. Sugerman, Gladstone, N. vJ., andJerome L. Been, Brooklyn, N. Y., assignors to Rubber and Asbestos Corp,Jersey City, N. 1., a corporation of New Jersey Application December 1,1947, Serial No. 789,050v

4 Claims. 1

The present invention relates to a method of forming brushes andparticularly to fixing bristlesby embedding the bristle ends in anadhesive substance. It is known in the art to mold brushes by casting aresin in a mold which also supports bristles, but such practice has thedisadvantage of using costly machinery which is slow and difficult tooperate particularly since the resin may exude around the bristleperforations in the mold and removal from the mold is difficult if notimpossible, particularly in the case of round or rotary brushes.

As a primary feature of this invention, the adhesive is cast and in apreferred form is thermoset as by vulcanizing using a frangible form aspart of the mold which temporaril supports the bristles or tufts thereofin position in the mold, the frangible member being subsequentlydestroyed as it is removed from the com pletely formed brush after theadhesive has set.

The invention overcomes the difficulty of adhesively setting by molding,brushes of odd shape, particularly round or rotary type brushes, but theprinciple of the invention will obviously be applicable to other typesof brushes.

It is accordingly a primary object of this invention to provide a methodof casting a resinous binder for brush bristles.

It is a further object to mold the resinous binder with a temporary,frangible mold. body capable of supporting the bristles for adhesion tothe brush body of any desired shape, but particularly round or rotarybrushes.

It is a further object to provide a temporary frangible mold body whichwill not adhere to the resinous binder and may be easily removed.

The invention is explained in further detail by reference to thedrawings which are illustrative of application to two types of brushes,but it will be understood that other types of brushes may be madaccording to principles herein. v I v v The several figures of thedrawing illustrate the several stages of constr'uction'accordin to thepresent process.

Fig. 1 shows a core member of a rotary or round type of brush prior tosetting the bristles thereon.

Fig. 2 shows the core member with part of the frangible mold mountedthereon prior to adding the bristles and adhesive.

Fig. 3 is a transverse section on the line 33 of Fig. 2 with bristlesmounted in the, frangible mold element prior to filling the mold with adhesive.

Fig. l is the same as Fig. 3 after the mold is filled Withadhesive.

set forth Fig. 5 is the. same as Fig. 4 after the adhesive is set andthe frangible mold element is removed to produce the completed rotarybrush.

Fig. 6 is a hollow brush back of a flat brush to which bristles are tobe adhered.

Fig. '7 shows the mounting on the back of Fig. 6 of a frangiblemoldelement.

Fig. 8 shows the next step of inserting the bristles or tufts prior tocasting adhesive.

Fi 9 shows the completed brush after casting, setting and removing thefrangible mold element.

Th core element of Fig. 1 is a round metal, wood or plastic body orback, preferably a metallic bar or tube [0 which has a desirablyroughened surface ll formed .by knurling, indenting, corrugating, orotherwise for securing firmer adhesion of the plastic thereto. At eachend is a flange l2 lending strength and forming the ends of a mold. Thecore is further fitted with spindles l3, which are attached tov theflanges l2 through hubs i4 when the brush is to be mounted for rotation.

As shown in Fig. 2 a frangible element 15 is closely fitted over thecore extending from flange to flange to complete the molding spacebetween the core tube l0 and frangible element 15 and bounded at eachend by flanges l2. The frangible element [5 is generally composed ofeasily destructible vmaterial such as heavy laminated paper orcardboard. It may be made of light wood or plastic or combinationsthereof, preferably some material to be disposed of after moldingwithout great cost.

The frangible material will be of variable thickness depending on thenature of the material to firmly support the bristles and provide anouter mold surface during casting of the adhesive against possibly some,but not considerable pressure.

The frangible material is desirably of a nature to which the bristleadhesive will not adhere, but for this purpose the frangible materialmay be given a coating of adhesive repellent on the inner mold surfaceIt such as with conventional mold lubricant like zinc stearate, siliconegrease,

or regenerated cellulose.

; through which the bristles are firmly but temporarily mounted foradhesion to the core by subsequent casting.

After emplacing the frangible element on the core to form the mold asshown in Fig. 2, the bristles l8 are firmly packed into each perforationll so that the holes are completely filled and to prevent exudation offluid adhesive. The bristles I! are inserted until the inner endscontact the tube which forms a backing element therefor. The bristlesmay be individual as shown or may be inserted as bent tufts (not shown)as is conventional in. the art. The assembly prior to casting theadhesive resin is shown in Fig. 3.

The resin may be any liquid, liquefiable resin,

liquid resin forming substance which is .thermoplastic or thermosetting. That is the resin is normally liquid and is set after castingby heating to moderate temperatures, or the resin is naturaly solid butis liquefied prior to casting by heating to obtain sufficient fluidityfor pouring or extruding into the mold.

In the thermosetting category are Bakelite intermediates and ureaaldehydes, and natural and synthetic rubbers or blends thereof, butparticularly preferred is depolymerized rubber which may be produced inany desired practical degree of normal temperature fluidity and set orcured with sulphur by the usual methods.

Suitable thermo-plastics are the polystyrenes, polyvinyl halides,esters, acetals and mixtures, chloro-rubbers, alkyds and linearpolyamides. Some of these resins may be applied in the unpolymerized orpartially polymerized state and polymerization completed by curing inthe mold. K

For purposes of introducing the fiuid resin into the mold, one of theflanges [2 of the core is bored at [9 and 29. The liquid resin is thenintroduced into the mold through one of the openings as H) while theother opening as serves as a vent to allow the air to be displaced fromthe mold by the liquid resin.

The hot or cold liquid resin is then poured or otherwise injected intothe mold. If desired, the mold may be vibrated to displace air bubbles.In the case of thermosetting resins and rubbers the cast resin is heatedto the optimum temperature for curing or setting which will varydepending upon the nature of the resin.

After the resin is cast, set and cooled, the

frangible mold element 15 is removed by tearing, breaking and strippingfrom the finished brush. Fig.4 shows the cast resin 2| in the mold andFig. 5 shows the completed brush after breaking away the frangible moldelement l5.

Similar treatment may be applied to other types of brushes asillustrated for a flat brush in Figs. 6, '7, 8 and 9.

Thus Fig. 6 shows the back 22 of a typical fiat brush having a handle 23and hollowed out portion 24 forming the mold space, one wall of thebrush back being bored at 25 for introduction of resin 2|. Fig. 7 showsthe next stage of completing the mold by application of a frangible moldelement 26 perforated at 21 in desired pattern for reception of bristlesIS. The bristles are packed into the perforations as shown in Fig. 8

While the bristles fill the perforations and prevent exudation of liquidresin, when the resin is a dry powder or not very fluid, it maysometimes 4 be preferred to fill the mold first with resin and theninsert the bristles.

The following examples show typical operations with specific resins:

Example 1 The rotary type brush mold assembled as shown in Fig. 3 with afrangible mold element consisting of medium heavy gauge cardboardlaminate having thin cellophane film adhered to its inner mold surfaceis filled with a liquid resin of the following composition:

Parts by weight Depolymerized rubber Sulfur 40 Naftolen R-lOO l0Diphenyl guanidine 2 The filled mold is then vulcanized and cured byheating at C. for 18 hours. Thereafter the frangible cardboard is tornoff to give the completed brush a highly desirable bristle setting ofsuperior adhesion, high impact strength and abrasion resistance.

Example 2 In this case a cardboard element having its inner mold surfacetreated with plasticized silicone, a resin repellant availablecommercially as Dow-Corning Silicone Grease #DC-? is used as thefrangible element. The following resin composition is introduced intothe mold:

The filled mold is then cured by heating at 60 C. for eight hours.Thereafter the frangible mold element is torn off to give a strongly setbrush.

Considerable variation of the materials of the brush core or back ispossible as well as the materials comprising the bristles. The bristlesmay be natural hair, nylon, wynene tampico or other known types.

In certain cases it may be feasible to introduce the resin as a powderand cure similarly by heat, but such procedure does not give theexcellent bristle binding set forth according to the preferred procedureabove.

Various modifications are possible within the applicable scope of theinventive principles herein set forth, and it is intended accordinglythat the examples be deemed illustrative and not limiting except as setforth in the claims.

What is claimed is:

l. The method of forming brushes comprising temporarily assembling apreformed brush back, having flange extending from the edges thereof todefine a hollow portion therewith, with a frangible perforated closuremember extending across said flanges and thereby form an enclosedmolding cavity in the brush back, said frangible closure member beingcoated with an adhesive repellent substance, said perforated closuremember having inserted a tuft of bristles in each of said perforationsto a point whereby the inner ends of the bristles within said moldingcavity substantially contact the opposite surface of said hollow backportion of said brush, each tuft containing sufiicient bristles tofirmly pack each perforation and thereby support each tuft within theperforation and seal the perforation in fluid-tight manner, introducinginto said molding cavity a normally liquid elastomeric composi tionsettable to a solid by application of heat thereto, whereby the innerends of each tuft within the molding cavity become embedded within theliquid composition filling the same, heating the brush and heat settableliquid within the molding cavity therein to set said composi tion to asolid in bristle supporting and bonding relationship within the brushback, and destructively removing said frangible mold element from thefinished brush.

2. The method of forming brushes comprising temporarily assembling apreformed brush back, having flanges extending from the edges thereof todefine a hollow portion therewith, with a frangible perforated closuremember extending across said flanges and thereby form an enclosedmolding cavity in the brush back, said frangible closure member beingcoated with an adhesive repellent substance, said perforated closuremember having inserted a tuft of bristles in each of said perforationsto a point whereby the inner ends of the bristles within said moldingcavity substantially contact the opposite surface of said hollow backportion of said brush, each tuft containing sufficient bristles tofirmly pack each perforation and thereby support each tuft within theperforation and seal the perforation in fiuidtight manner, introducinginto said molding cavity a normally liquid heat settable depolymerizedrubber containing a vulcanizing agent, whereby the inner ends of eachtuft within th molding cavity become embedded within the liquidcomposition filling the same, heating the brush and heat settable liquidwithin the molding cavity therein to vulcanize and set said compositionto a solid in bristle supporting and bonding relationship within thebrush back, and destructively removing said frangible mold element fromthe finished brush.

3. The method of forming a rotary type brush comprising temporarilyassembling a preformed brush back, comprising a metallic cylindricalbrush back member having its surface roughened to enhance adhesion to acomposition molded thereto, and having circular flanges mounted near theouter ends thereof coaxial therewith, together with a cylindricalfrangible perforated closure member having a larger diameter than thefirst cylindrical member and mounted between said fianges and coaxialwith said first cylindrical member to form an enclosed molding cavitywith said flanges and said first cylindrical brush back member, saidfrangible closure member being coated with an adhesive repellentsubstance, said perforated closure member having inserted a tuft ofbristles in each of said perforations to a point whereby the inner endsof the bristles within said molding cavity substantially contact theopposite surface of said hollow back portion of said brush, each tuftcontaining sufiicient bristles to firmly pack each perforation andthereby support each tuft within the perforation and seal theperforation in fluidtight manner, introducing into said molding cavity anormally liquid elastomeric composition settable to a solid byapplication of heat thereto, whereby the inner ends of each tuft withinthe molding cavity become embedded Within the liquid composition fillingthe same, heating the brush and heat settable liquid within the moldingcavity therein to set said composition to a solid in bristle supportingand bonding relationship within the brush back, and destructivelyremoving said frangible mold element from the finished brush.

4. A rotary-type brush comprising a cylindrical metal core having aroughened surface and a pair of circular flanges mounted near the outerends thereof coaxial therewith, a plurality of tufts disposed normal tosaid cylindrical surface with the inner ends contacting the same forradial support and disposed in a pattern over substantially the entirecylindrical surface, said tufts being embedded within a solid vulcanizednormally liquid depolymerized rubber composition disposed as acylindrical layer between and substantially filling the cylindricalvolume from flange to flange and firmly supporting and elastomericallycompressing each tuft at the cylindrical surface juncture therewith,whereby said brush comprises a smooth cylindrical vulcanized rubber bodycontaining bristle tufts disposed thereabout and resiliently embeddedtherein.

BERNARD E. SUGERMAN. JEROME L. BEEN.

REFERENCES CETED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 717,014 Morrison Dec. 30, 1902737,970 Schwartz Sept. 1, 1903 1,394,255 Davis Oct. 18, 1921 1,402,990Adams Jan. 10, 1922 1,556,298 Morck Oct. 6, 1925 1,595,006 Kelly Aug. 3,1926 1,886,759 Taylor Nov. 8, 1932 2,094,008 Freedlander Sept. 28, 19372,427,137 Hall Sept. 9, 1947

